Method of and apparatus for dusting fibrous material



`Iuly 20,1943. E. LUNbGRN l, A 2,324,787

METHOD OF AND APPARATUS FOR DUSTING FIBROUS MATERIAL Filed Jan. 22,l 1940 nz/E'HUF f "fric Luhcfgrefz Patented July 20, 1943 UNI-TED STATES PATIENT OFFICE METHOD oF AND APPARATUS Fon DUSTING v Famous MATERIAL Eric Lundgren,Braddocky Heights, Md., assigner Company, Burlington,

, Vt., a corporation of vement I Application 22, 1940, Serial No, 314,961

15 claims. (ci. 117-19) apparatus for dusting fibrous material. More particularly, theinvention relates to the dusting with talc, soapstone, or the like, of a traveling web of a rubberized fibrous material to eliminate the stickiness-of the rubberized fiber.

In the preparation of webs of rubberizedv fibrous material, the web of material is sprayed with rubber latex, or the latex otherwise applied thereto, and the moisture eliminated from' the latex by evaporation at ordinary temperatures or at'the more elevated temperatures of a drying This invention relates 4to a method of and the circulating stream of gas orair.

gas or air and also with a provision for reincorporating fresh supplies of the dusting agent into laden -gasstream is maintained under a subat- `mospheric pressure'during its'passage through the web of fibrous open mesh material so as to or vulcanizing chamber. Owing tothe tacky or sticky nature of the rubberized fibers so produced, it is desirable to dust the material in order to eliminate this residual sticlriness. While it would be a simple matter merely to spray or sprinkle a throughout the body of the fibrous material, par-A ticularly where the fibrous materialy is of substantial thickness. The tendency is for most of the powder to be retained on' the fibers nearest thesurfaces of the web against which the powder is applied, with little, if any, of the powder penei trating through to thebers on the inside `of the web.

In accordance with my present invention, I provide a method/of and an apparatus for applying prevent the escape of the dusting agent from the circulating system. 1

It is therefore an important object of `thisinvention to provide a method for applying a powder, perfume or other treating ageht'innely divided form to open mesh material in such a way thatthe treating agent is uniformly distributed over the surfaces of the open mesh material eve though thelatter be relatively thick. f

It is afurther'important object of this inven` tion to provide a methodwherein the dusting agent is carried by a stream of gas or air confined within a substantially closed circulating system, with kthe open mesh material toibe impregnated passing through a' portion of the sysopposite directions. l l

It is a further important object ofl this invention to provide an apparatus particularly adapted a dust, powder, perfume, or other treating agent,

in a nely divided form to a porous, .open mesh body, such as a web of rubberized fibrous material, whereby the treating vagent is uniformly api plied to all of the surfaces throughout the entire body of the open mesh material. My process is` particularly applicable to the dusting of a rubberized fibrous material with powdered talc or soapstone to obtain complete coverage of the rubberized surfaces so as to prevent undesired stickmaterial which is to be treated.` This is accomplished by suspending the dusting agent in a ystream of air or other gas and drawing the thus laden gas stream through the open mesh material, preferably so as to pass completely through `for the application'of a powder, perfume, orother finely divided treating agent to afweb" of open mesh material,A with the provision in su'ch appa'- ratus of a housing for substantially enclosinga portion of the web of open` mesh material and Vwith the provision also of means fordrawing a i surfaces thereof.

the material from opposite sides at spaced points along the travel of the material if it is vin web form. The machine further includes a ,recirculating system for lthe gas` stream, with provision' for withdrawing from the system any excess of It is a further important :object of this invention to provide a housing for substantially enclosing a portion of a traveling web of` openmesh material, the housing being so constructed as to cause a stream of `gas or air laden with a finely divided treating agentto pass completely through the traveling web of open mesh material from opposite sides thereof at spaced points along the travel vof the web. t t

It is a further important object of this invention to provide an apparatus defining a `substantially closed circulating system for dustladen air, with means within the system for conducting the stream of such dust laden air, whilemundr subatmospheric pressure, completely through `a portion of a traveling web of open mesh material The dust v the travel of said web in order to insure thorough and uniform distribution of the dust upon all surfaces of the open mesh material.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawgThis invention (in a preferred form) is illustrated in the drawing and hereinafter more fully described.

On the drawing:

Figure 1 is a. schematicview, in elevation, of apparatus embodying the principles of my invention.

Figure 2 is an enlarged sectional view taken substantially on the broken line II-II of Fig. 1.

Figure 3 is a. fragmentary enlarged sectional view taken substantially on the line III-III of Fig. 1.

As shown on the drawing:

The reference numera1 III indicates a web of open mesh material, such as rubberized Tampico fiber, hair, or other fibrous material, or sponge rubber, which is to be treated in the apparatus by the method of my invention. Although my method is applicable to the treatment of single sheets or batts of open mesh material, its greater utility lies in the treatment of a continuous traveling web of such material. My invention will therefore be described as a part of a machine, or as a step in amethod, for the continuous production of a web of open mesh material. As previously stated, an example of the application of my method is the dusting of a web of rubberized intermingled fibers with talc, -soapstone, or the like, or with perfume, during the course of its manufacture.

A housing, generally indicated by the reference numera1 II serves to substantially enclose a portion of the traveling web I while' permitting free travel of the web therethrough. Said housing II comprises a pair of chambers I2 and I3, positioned below the web I0 and spaced apart by a connecting, horizontal wall portion I4. 'I'he chamber I2, constituting an entrance chamber, is provided with an upper horizontal flange or lip I5 extending parallel to and tangentially of the web I0, and the chamber I3 is provided with a similarly disposed flange or lip I6. The upper surfaces of said wall portion I4 and of said lips I5 land I6 serve to support the web I0 in its travel upper walls of the chambers I 2 and-I3 and which are spaced slightly from the lateral edges of the web I0. A cover or hood 2| rests upon the side members I9 and 20. Said cover 2I is provided with horizontal wall extensions 22 and 23, which together with the horizontally disposed flanges or lips I5 and I6, respectively, form constricted passages through which the web I0 travels with only a minimum of binding effect. The intermediate body portion of the cover 2I is spaced above the web I0 to provide a turning chamber 24 for the gas or air passing therethrough.

A blower 26 is connected by means of a conduit side of the traveling web I0.

21 to the exit chamber I3 for drawing a stream of 75 dust laden air, or gas, through the housing II. Saidfblower 26 discharges `the dust laden air or gas into a conduit 26 that leads into a conventional type of dust separator 29. From the top of the dust separator=29, a gas conduit 30 leads back into the entrance chamber I2. A dust return line 3| leads from the bottom of the dust collector 29 also to the chamber I2.

In order to remove .from the circulating system any excess of air that may be drawn into the housing II through the passageways E and D provided by the cooperating horizontal wall portions I6 and 23, and I5 and 22, there is provided a conduit 33 through which excess air is conducted from the conduit 30 to a suitable type of lter or collector 32. vAfter passing through filter elements 34, air from which the dust has been removed is discharged through an exhaust 35. Suction may be applied to the exhaust 35 if necessary. Dust collected in the separator 32 is carried by gravity through aconduit 36, as-

sisted by a. certain amount of air or gas flowing reservoir or receptacle 31, provided with a gate valve 38, or other means for regulating the discharge of the treating agent therefrom into a conduit 39 leading into the intake chamber I2. Although the reservoir is shown, for convenience, at a lower level than the chamber I2, it may actually be elevated thereabove in order that the dust may be fed by gravity, or any type of dust feeding mechanism may be employed.

In operating the apparatus just described, the blower` 26 is first started up to cause a circulation of air or gas, withdrawn from the housing Il, through the system including the conduit 28, the dust collector 29, and the conduit 30 back to the entrance chamber I 2. Dust lfrom the storage receptacle 31 is introduced into the circulating system by proper regulation of the gate valve 33, the dust entering the intake I2 being there picked up -by the stream of air entering thereinto through the conduit 30.

The dust laden air passes upwardly through the passageway I1 in the direction of theunder- Most of the dust laden air passes completely through the open mesh web I0 into the turning chamber 24, but some small proportion of the dust laden air may flow through the open meshes of the web I0 longitudinally thereof andthus nd its way into the exit chamber passageway I8 with entering the turning chamber. The dust laden air flowing into the turning' chamber 24 has its direction reversed and passes downwardly in the direction 0f the arrows into the passageway I8 and thence into the exit chamber I3. From the exit chamber I3, the air is withdrawnunder the suction effect of the blower 26 and continues through the cycle just described.

The stream of air passing through the housing II is preferably maintained under a pressure slightly less than atmospheric, for the purpose of preventing the escape of dust therefrom into the surrounding atmosphere. Accordingly, there is a slight leakage of air into the system through the entrance passageway E, formed by the flanges I6 and 23, and through the exit passageway D, formed by the flanges I5 and 22. Also, since the web I0 is of open mesh structure, a certain amount of air is pulled into the housing I I throughthe web material itself.

In order to remove from the system the excess of air-so drawn in, a portion of the air stream within the conduit 30 is allowedl to pass out through the conduit 33 into -the collector 32, from which dust is returned to the entrance chamber `from the system except that lpi/tked, up by, the

traveling web I0, and any loss is replaced by admission of fresh dust from the supply reservoir 31. y.

Since the dust ladenA Stream of air is passed completely through the traveling web I0, rst in lo-ne direction and then in the other, a uniform distribution of the dust over the surfaces of the web and throughout the body thereof is insured. The amount of suction produced by the blower `iiI can be so regulated as to prevent any substantial excess of dust adhering to the surfaces ofthe web I- as it leaves the exit passageway D, since with the higher `velocities and lower pressures within the housing I I, any loose dust on the surfaces of the web Il) will tend to be drawn inwardly into the housing, instead of `being permitted to remain on the web surfaces as it leaves the hous-4 ing. There may also be a slight ow of dust laden i air longitudinally through the web I0 owing to its great porosity. Consequently, there is complete penetration of the dust laden air stream into all y of the interstices of the open mesh web material.

It will, of course, be understood that various details of construction may bervaried through4 a wide range without departing from the principles of this invention and it is, therefore, not the purpose. to limit the patent lgranted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. The method of dusting. a batt of porous material, which comprises passing -a dust laden gas lcompletely through said material from one side I to the other and back again and maintaining said gas during such passage under less than atmospheric pressure.

2. The method of treating a travelingweb of open mesh porous material with a finely divided 3. The method of treating a traveling web of open mesh porous material with a finely divided agent, which comprises suspending said finely divided agent in astream of a gas, passing said laden gas stream backv and forth through said traveling web, maintaining said `gas stream during lsuch passage back and forth under a pressure slightlyV lower than atmospheric pressure, replacing the amount of said agent taken out of said stream by said traveling web, and bleeding .out of said gas stream any excess of gas drawn thereinto dueto the subatmospheric pressure.

4. The method of applying talc and the like to a traveling web of rubberized open mesh fibrous -material, which comprises suspending nely divided talc in an air stream, directing said talcladen-air stream through said traveling web from opposite directions spaced lengthwise of said web and maintaining saidair stream underless than atmospheric pressure while passing through said web to draw air from the outsideinto said stream andprevent escape of the talc therefrom into the atmosphere.

5. The method of applying talc and the lil"e to a traveling web of rubberized open mesh brous material, which comprises suspending finely` .di-

' vided talc in an air stream, directing said talcladen air stream through said traveling web from opposite directions spaced lengthwise of said web,

lseparating-talc from the air stream after leaving said webv and reintroducing such separated talc into said air stream prior to repassage -through and bleeding out of said system excess air substantially free from said dusting agent.

7. In a machine of the class described, a housing for enclosing a portion of a traveling web of porous material having an inlet and outlet on the same side of said web and a cover plate on the opposite side spanning saidinlet and outlet and having ends spaced from said housing by the through said web for discharge through saidoutlet.

8. In a machine of the class described; a housing for enclosing a portion of a traveling web of porous material having an inlet and outlet on the same side of said web and a spaced cover plate on the opposite side spanning said inlet and outlet, means for introducing a stream ofl dust laden gas into said housing inlet for passage through said enclosed web portion and between said cover and webr and back through said web for discharge through said outlet and'means for maintaining the stream of gas under subatmospheric pressure during passage through said housing.

9. In a machine for dusting a traveling web of porous viibrous material, a housing substantially enclosing a portion of said web and having an inlet and outlet on the same side thereof, said housing including a cover plate on the other side thereof. spanning said inlet and outlet and` supported by said housing at a level such as to define an air space between said web and said cover plate, a mixing chamber connected to said inlet and means connected to saidoutlet for Vsucking `a dust-laden stream ofair from said mixing chamber through said housing for passage through a web portion enclosed thereby, through said air space; back through another portion of said web and through said outlet,

10. In a machine for dusting a traveling web of porous fibrous material, a housing substantially enclosing a portion of said web and having an'inlet and outlet on the same side thereof, said housing including a cover plate on the other side thereof spanning said inlet and outlet and supported by said housing at a level such as to dene by, through said air space and back through another portion of said web and through said outlet, a separator beyond said suction means 'and in advance of said mixing chamber for removal of some of said dust prior to the return of the air stream to said mixing chamber, conduit means connecting said sucking means and said outlet, and further conduit means'connecting said separator with said sucking means and with said mixing chamber. v

11. In a machine for dusting a traveling web of porous fibrous material, a housing substantially enclosing a portion of said web and having an inlet and outlet on the same side thereof, said housing including a cover plate on the other side thereof spanning said inlet and outlet and supported by said housing ata level such as to denne an air space between said web and said cover plate, a mixing chamber connected to said inlet, means for sucking a dust-laden lstream of air from4 said mixing chamber through said housing for passage through a web portion enclosed thereby, through said air space, back through another portion of said web and through said outlet,`a separator beyond said suction means and in advance of said mixing chamber for removal ol.' some of said dust prior to the return of the air stream to said mixing chamber, conduit means connecting said sucking means and said outlet, further conduit means connecting said separator with said suction means and with said mixing vasaasvlrr chamber, and means for bleeding exces air out of the air stream from which dust has been removed prior to the return of the air stream to said mixingchamber.

12. The method of dusting a material which comprises establishing a U- shaped stream of dust laden gas and passing said n shaped stream of dust laden gas and passing said sheet transversely through the legs of said U- shaped gas stream at a height such that the bight of said U-shaped gas stream will sweep over the surface oi said sheet.

15. The apparatus for dusting a sheet of porous material which comprises means for establishing a stream of dust laden gas, a U-shaped conduit for said gas stream, and means for passing said sheet transversely through the legs of said U- l shaped conduit at a height such that the gas stream will sweep over the surface of said sheet.

ERIC LUNDGREN.

sheet .of porous 

